Leakproof dry cell



Feb. 13, 1951 D. McAcHRoN ETAL LEAKPROOF DRY CELL Filed July 9, 1947 wwwPatented Feb. 13,1951- dgar D. McEachron, "George Il. Schroeder, andHenry G.

Edgar J. McEachron,

Wausau, Wis., assignors to Marathon ,Battery Company, Wausau, Wis., u.corporation of Wiscousin Application July 9, 1947, Serial No. 759,890

This invention relates to improvements in'elecytrlcal dry cells and moreparticularly to an improved constructiontherefor which prevents theexudation or leakage of any part of the contents of such a cell andtherefore eliminates possible damage to associated equipment.

v.'Io prevent such leakage in dry cells of the type which have beenwidely used in flashlights has becomeA increasingly important, sincesuch cells are also now being used-in equipment of considerably greatervalue, such as hearing aids or portable radio receivers. f

Numerous types of construction have been del veloped with the idea inmind of eliminating the danger of .cell leakage. In most of these typesof construction yit has been necessary to sacrifice Y some of the otherdesirable characteristics of the cell in order to obtain a non-leakingvariety. For

instance, in the ty'pe of construction utilizing the double 'zinc cup,the size of the inner can and the bobbin of depolarizing material andthe volume of electrolyte have necessarily been reduced. This is true,since the outside dimensions. of flashlight cells have been standardizedby the industry for obvious reasons. Therefore any inof an all metaldouble-wall construction without 'A the expense of a metal jacket orsecond cup.

It is therefore the object of this invention to provide a practical,inexpensive and elllcient cell having a protective casing whichentirelyeliminates the danger of leakage from the cell and whichconsequently eliminates the disadvantages which result from suchleakage. Y j

It is a further object to provide a cell ofthe character describedwithout sacricing other desrable characteristics such as reducing thevolume of active ingredients contained therein.

Y An additional object is to provide an electrical dry cell which is ofleak-proof construction but which may be manufactured at a costcomparable with cells of the non-leak-proof variety.

Further objects and advantages of this invenn tion will become evidentas the description proceeds, and from an examination ofthe accom- 5claims. (o1. 13s-133) panying drawingjwhlch illustrates one embodimentof the invention and in which similar numerals refer to similar partsthroughout the several views. v,

In the drawing- Fig. 1 is a vertical sectional view of a dry cellembodying one form of this invention;

Fig. 2 is an exploded view of the various parts making up the dry cell.as shown in Fig. 1, the parts being shown in their appropriate verticalrelation to each other;

Fig. 3 is a top plane view of the cell shown Fig. 1.

' Referring now to Figures 1 andz, the dry cell has the zinc cupelectrode III which contains the usual bobbin I2 and the electrolyte M.The electrolyte il is disposed between the outer surface of the bobbinI2 and the inner surface of zinc cup I0. A carbon' electrode I6 iscentrally disposed in the depolarizing material forming the mam body ofthe bobbin l2 and projects froml the upper end of the latter. vTheinsulating disc .The disc 22 is preferably of vulcanized i'lber and hasat least its underside coated with a suitable protective material 26,such as one of several grades of vinylite nishes which are well known inthe art which are resistant to the action of the materials within thecell.

A suitable thermoplastic material 30, such 'as the usual asphaltcompound, is poured over the disc 22 while in a plastic condition andallowed to solidify to form a `seal above this disc. The cap 32of'suitable metal may be force-fitted over the carbon electrode I6 priorto the application of this thermoplastic material 30 so that its loweredge extends into the material 30 when the latter has solidified, asshown in Fig. 1.

A thin resilient sheath or film 36 which may be formed of any suitablerubber-like substance which is substantially impervious to the materialswhich may exude from the dry cell, together with a jacket 38 formed ofpaper or other suitable in-l expensive material to which the sheath 36is internally secured, is then placed over the zinc cup. This film 36and the paper jacket 38 are preferably of a pre-formed construction andmake up a laminated cover for the zinc cup. The film I8 is secured tothe inner surface of the paper jacket 38 with a suitable cement prior tothe time the laminated cover is slipped over the can III. The laminatedtube is of the same length as the zinc cup I Il so that the upper andlower edges of the tube are ilush with the upper edge and the base 28 ofthe cup I0, respectively.

A second disc 34 which has a central opening 35 adapted to enclose thecap member 32 is then fitted over the protruding carbon electrode I6 andseated on the upper edge of the zinc can I0, the sheath 36, and thepaper jacket 38.

The anged closure 40, which may be of a construction similar to thatdisclosed in the McEachron et al. Patent No. 2,332,456, is then placedin abutting relation with the disc 34 so that the peripheral edge of thecentral opening 42 in the closure is in spaced relation to thecircumferential side of the cap 32 on the carbon electrode I6, and theange 4I extends downwardly adjacent the paper jacket 38. The ilange 4Iof the closure 40 is then crimped inwardly so as to engage theperipheral edge of the disc 34, together with the upper edges of thejacket 38, the film 36 and the zinc cup I0. As shown in Fig. 1, the disc34 serves to insulate the upper edge of the zinc cup I from the mainbody of the metal closure 48, and the upper vedge of the paper jacket 38serves to insulate the crimped, peripheral edge of the closure.

40 likewise from the cup I0. This disposition of the metal closure 48effectively seals the open end of the cell. The film 36 is alsoeffectively sealed against the zinc cup I0 at the point at which theperipheral edge of the closure 40 is crimped inwardly. 'This is truesince, as shown in Fig. 1, the inward crimping of the closure 40 alsoresults in a crimping of the upper edge of the zinc can I 6 and theupper edge of the paper jacket 38.

' The upper edge of the film 36 is therefore effec-` tively compressedby the crimped paper jacket againstY the correspondingly crimped portionof the zinc cup.

This inward displacement of the zinc cup I0 occurs immediately-above thedisc 22, so that the latter is effectively locked in place by the bead26 and this displacement. The presence of the thermoplastic 30 togetherwith this locking action insures a tight seal between the zinc cup I0and the disc 22 around its peripheral edge.

A flanged ring 44 with a, large central opening 46 is then slipped overthe bottom Yof the cell with the insulating ring washer 45 therein sothat it encloses the bottom edge of the jacket 38 and is ush against thewasher 45 which is, in turn, ad-

jacent the base 20 0f the zinc cup I0. The flange on this ring is thencrimped tothe bottom of the cell, effectively sealing the film 36 to thezinc cup I0 in substantially the same fashion as described above inconnection with the sealing action of the closure member 40. After thering is so disposed it is electrically insulated from the zinc cupelecrode IU just as is the closure v40. The crimping of the flange onthe ring 44 also displaces the jacket 38 and the zinc cup I6 to form thebead 48 immediately above the insulating disc I8.

From the above description it will be seen that the zinc cup Ill istightly enclosed by the laminated tube made up of the paper jacket 38and the lm 36. Since it sometimes happens in this type of dry cell thatthe zinc can is partially consumed and corroded during the normal use ofthe cell, with the result that'the electrolyte housed within the can isforced or otherwise leaks out of the zinc can to the exterior thereof,some suitable method of confining these exudations is A characteristicof such cells.- In case perforation of the zinc cup occurs, the materialforced through to the external surface of the cup will be dispersed overthe entire outside surface of the cup between the latter and the film36, since such material is of a fluid or semi-fluid nature. The pressureseals between the lm 36 and the zinc cup I 0 described above willmaintain such exuded material in the larea between these circumferentialseals, and the lm 36, being impervious, will prevent it from passingthrough to the paper jacket.v y

Due to the generation of gases within the cell during the period of use,considerable pressure is often built up in the interior of the cell.This pressure often forces the electrolyte out through any perforationswhich may have been formed in the zinc can. It is therefore importantthat any material which is utilized to confine this exuded material hassufficientl strength to withstand such pressure as it is built upwithout becoming distorted. This material should be such that it permitsno appreciable'swelling to take place, for instance, sincevaluable'equipment can be damaged as readily by such swelling as by thecorrosive eiects of the exudations. Byfcrimping the paper cover at eachend so that it isvtightly compressed against the zin-c can, it isnormally held under a slight longitudinal tension. This tension tends toresist any outward displacement of the cover such as thatl which mightoccur when the electrolyte or other material is forced out lof the zinccup into the area between the cup and the film.

Although the film 36 does not extend beyond the bottom edge of the zinccan I6 and the base of the can 20 is `therefore expcsed through thecentral opening 46 in the flanged ring 44, there is no danger of leakageat this point. This is true because the insulating disc I8 is composedof a material which protects the base 20 from the chemical action whichordinarily takes place on the sidewall within the cup. 'I'he base istherefore protected from possible corrosion and resultant leakage.Furthermore, since there is a circumferential seal between the film 36and the zinc can I0 adjacent to the base of the can, exuded materialcannot leak down from the sides of the can into contact with theexternal surface of the base 20 of the can. This construction of thebottom portion of the dry cell not only eliminates the danger of leakagein this area but also provides a simple method of producing a circuitterminal at the bottom end of the can.

It has been found desirable to pre-form the lm 36 and the paper jacket38 as a laminated tube prior to dispo-sing either the film or the paperjacket on the zinc cup Il). If the film 36 is handled independently itis much more difflcult to maintain it in the proper shape in order toeasily insert the zinc can I0 therein. For instance, a tube of suchmaterial has a tendency to remain collapsed in the form of a flat stripwith the two sides of such strip adhering firmly to each other. Openingthis collapsed tube and maintaining it in such an open form is a problemwhich causes diiiiculty in a mass production technique. In addition, ithas been found that it is impossible under current methods ofmanufacture to produce a tube of suitable resilient material which hasdimensions .accurate enough 1 to make it satisfactory the ytolerancesmust be qultef'small. Also, the Adimensions .of most materials of thisgeneraltype are radically affected by-changes in temperature,

5 for this typeof use, where so that it' would be necessary tov closelycontrol the room temperature during the manufacturing process. A

Under the preferred procedure the formation of the laminated tube can becarried out by spirally winding a strip of suitable rubber-like materialon a mandrel so that its edges overlap. These edges are then sealed byheat or a suitable adhesive to form the illm 36. Thereafter asuitableadhesive is also applied to the outer surface of this resilientmaterialand a strip ofpaper or like material is spirally wound thereover to formthe jacket 38. The completed tube is then cut to the proper lengthswhich are removed from the mandrel and the individual sections so formedmay then be slipped over the zinc cup to form the protective coveringdescribed above.` 'Ihe flanged metal closure is then spun in retainingengagement with the paper jacket and the side wall of the can at thetopof the cell, and the anged ring is similarly spun in place at the bottomof the cell, all in accordance with the description set out above.

The operations of inserting the cell into the section of laminatedcovering material and the spinning of the metal closure and the flangedring into the desired position are such that they lend themselves tobeing accomplished by high speed mechanical means. This fact plus theelim- Iination of a large portion of the metal usually ly engaging ,saidvcore electrode'- and said cui) electrode, a sleeve offlexible, rubberymaterial substantially impervious to-the possible exudations of said drycell non-adherently sheathing said cup electrodefa non-metallic `coversecured to and overlying said sleeve, a flanged metal ring closelyembracing the lower end of said dry cell, the flange onsaid ring beingin crimping engagement with the lower edges of said cover, said sleeveand said cup electrode, a disc of insulating material disposed betweenthe baseof -said core electrode and the inner surface of the baseol.said cup electrode, said crimping engagement 'of said flanged ring beingsuch that said electrode is inwardly displaced immediately above saiddisc so as to lock the latter against said base of said cup electrode, aflanged metal disc closely embracing the upper end of said dry cell. theflange on said disc being in crimping engagement with the upper .edgesof said cover. said sleeve, and said cup electrode, the crimped portionsof said anged disc and said flanged ring causing said resilient sleeveto be compressed between said cover and said cup electrode so as to forma tight pressure-seal between said sleeve and said cup electrodeadjacent its upper and lower ends, and means for insulating said flangeddisc and said flanged ring from said cup electrode.

adherently embracing the outside walls of said4 can. means for closingsaid can disposed inside thereof, said means closely engaging the`innerside Walls of said can and a flanged metal disc said carbon electrode,tightly embracing the upper end of said dry cell, the flange on saiddisc being v in' crimped relation with. the outside walls of said tion.Changes in form and in the proportion of A parts, as well as thesubstitution of equivalents are contemplated, as circumstances maysuggest or render expedient, without departing from the spirit or scopeof this invention.

What is claimed is: l

l. A non-leaking dry cell provided with circuit terminals at both endscomprising a metal cup electrode, a core electrode, meansfor closingsaid cell comprising a no-n-conducting material close- Ily engaging saidcore electrode and said cup electrode, a sleeve of flexible. rubberymaterial substantially impervious to the possible exudations of said drycell non-adherently sheathing said cup electrode, a non-metallic coversecured to and overlying said sleeve, a flanged ring closely embracingthe lower end of saidy dryv cell, the flange on said ring being incrimping engagement with the lower edges of said cover, said sleeve andsaid cup electrode, and a flanged disc closely embracing theupper end ofsaid dry cell, the flange on said disc being in crimped relation with lthe upper edges of said cover, said sleeve, and

said cup electrode, the crimped portions of said flanged disc and saidflanged ring causing said resilient sleeve to be compressed between saidcover and said cup electrode so as to form a tight pressure-seal betweensaidA sleeve and said cup electrode adjacent its upper and lower ends.

2. A non-leaking dry cellv provided with circuit terminals at both endscomprising a metal cup electrode, a core electrode, means for closingsaid' cell comprising a non-conducting material closecan so as tocompress and seal said sleeve against the underlying portion of saidcan, said flanged disc having an opening therein through which saidAcarbon electrode projects, and a flanged ring member tightly embracingthe lower end of said dry cell, the ange on said ring being in crimpedrelation with the outside walls of said can so as to compress and sealsaid sleeve against the underlying portion of said can, said flangedring having an opening in its bottom for exposing the bottom vof saidcan whereby the same may serve as an electrode.

12. A leakproof dry cell provided with circuit terminals at oppositeends, comprising ,a metal can serving as an electrode and containing anelectrolyte, a centrally disposed carbon electrode and depolarizing mixin said electrolyte, a lami- .fnated sheath having an inner layer ofthin, flexible, rubbery material which is resistant to penetration bysaid electrolyte non-adherently embracing the outside walls of said canand an outer layer of non-metallic material towhich said inner layer ofrubbery material is adhesively secured, means for closing said candisposed inside thereof, said meansbeing closely embraced by inner sidewalls of said can and closely embracing the sides of said carbonelectrode, a flanged disc tightly embracing the upper end of said drycell, the flange on said disc being in crimped relation with the outsidewalls of said 5 can above said means for closing said can so as havingan opening therein through which said carbon electrode projects, and ailansed ring member tightly embracing the lower end of said dry cell,the flange on said ring being in crimped relation with the outside wallsof said can so as to compress and seal said sheath against theunderlying portion of said can said flanged ring having an opening inits bottom for exposing the bottom of said can whereby the same mayserve as anV electrode.

5. In a leakproof dry cell containing an electrolyte, the combination ofa metal cup member serving as an electrode, a. laminated sheath having athin inner layer of flexible, rubbery material which is resistant topenetration by said electrolyte non-adherently embracing the outsidewalls 8 cup, a flanged disc embracing the upper-.edge of said cup, thenange on said disc being disposed in crimped engagement with the upperedge of said sheath, and a`disc ofy non-conducting material disposed soas to insulate said disc from said cup. v

EDGAR D. McEACI-IRON. EDGAR J. MCEACHRON. GEORGE H. SCHROEDER. HENRY G.FRIANG.

REFERENCES CITED The .following references are of record in the nie ofthis patent:

2,410,826 Lang et a1 Nov. 12, 194e Certificate of Correction Patent No.2,541,931 February 13, 1951 EDGAR D. MOEACHRON ET AL. It is herebycertified that error appears in the printed specification of the abovenumbered patent requiring correction as follows:

Column 6, line 39, strike out the Words a flanged metal disc and insertthe same after the Word and comma e1eotrode, in line 40; line 55, forthe claim numbered 12 read 4; and that the said Letters Patent should beread as corrected above, so that the same may conform to the record ofthe oase in the Patent Oice.

Signed and sealed this 5th day of June, A. D. 1951.

[SEAL] THOMAS F. MURPHY,

Assistant Gommzfssz'amar of Patents.

1. A NON-LEAKING DRY CELL PROVIDED WITH CIRCUIT TERMINALS AT BOTH ENDSCOMPRISING A METAL CUP ELECTRODE, A CORE ELECTRODE, MEANS FOR CLOSINGSAID CELL COMPRISING A NON-CONDUCTING MATERIAL CLOSELY ENGAGING SAIDCORE ELECTRODE AND SAID CUP ELECTREDE, A SLEEVE OF FLEXIBLE, RUBBERYMATERIAL SUBSTANTIALLY IMPERVIOUS TO BE POSSIBLE EXUDATIONS OF SAID DRYCELL NON-ADHERENTLY SHEATHING SAID UP ELECTRODE, A NON-METALLIC COVERSECURED TO AND OVERLYING SAID SLEEVE, A FLANGED RING CLOSELY EMBRACINGTHE LOWER END OF SAID DRY CELL, THE FLANGE ON SAID RING BEING INCRIMPING ENGAGEMENT WITH THE LOWER EDGES OF SAID COVER, SAID SLEEVE ANDSAID CUP ELECTRODE, THE CRIMPED PORTIONS OF SAID EMBRACING THE UPPER ENDOF SAID DRY CELL, THE FLANGE ON SAID DISC BEING IN CRIMPED RELATION WITHTHE UPPER EDGES OF SAID COVER, SAID SLEEVE, AND SAID CUP ELECTRODE, THECRIMPED PORTIONS OF SAID FLANGED DISC AND SAID FLANGED RING CAUSING SAIDRESILIENT SLEEVE TO BE COMPRESSED BETWEEN SAID COVER AND SAID CUPELECTRODE SO AS TO FORM A TIGHT PRESSURE-SEAL BETWEEN SAID SLEEVE ANDSAID CUP ELECTRODE ADJACENT ITS UPPER AND LOWER ENDS.